Snap action switch



Oct. 20, 1964 G. G. GUTHRIE SNAP ACTION SWITCH Filed May 29, 1963 FIG. I.

George G. Guthrie United States Patent 3,153,703 SNAP AUEIQN WlTCH George G. Guthrie, 1164 N. Vancouver, Tulsa 27, Okla. Filed May 29, 1963, Ser. No. 284,159 1 Claim. (Cl. 269-67) This invention relates to a snap action switch, and has as its primary object the provision of a switch which will, upon the exertion of force on an intermediate portion thereof, effect a substantially instantaneous opening of one electrical circuit and closing of another.

An additional object of the invention is the provision of a device of this character wherein the length of the path of travel of a contact arm eiiectuating the opening and closure of the circuits may be regulated to vary the elapsed time between the opening and closing of the circuits.

Still another object of the invention is the provision of a switch of this character which may be readily adapted to a wide variety of usages, which is sturdy and durable in construction, reliable and efiicient in operation, and relatively simple and inexpensive to manufacture, assemble and utilize.

Still other objects will in part be obvious and in part be pointed out as the description of the invention proceeds, and shown in the accompanying drawing wherein there is disclosed a preferred embodiment of this inventive concept.

In the drawing:

FIGURE 1 is a longitudinal vertical section taken substantially through the center line of one form of switch embodying the instant inventive concept shown, illustratively, in association with a pressure actuated diaphragm controlling a plunger.

FIG. 2 is a top plan view of the apparatus of FIG. 1 taken substantially along the line 2-2 of FIG. 1.

FIG. 3 is a sectional view taken substantially along the line 3-3 of FIG. 1 as viewed in the direction indicated by the arrows.

FIG. 4 is a perspective view of the contact arm assembly comprising an essential component of this switch.

FIG. 5 is a sectional view taken substantially along the line 5-5 of FIG. 4 as viewed in the direction indicated by the arrows.

REG. 6 is a side elevational view of the contact arm and spring stop assembly, and,

FIG. 7 is a fragmentary sectional view taken substantially along the line 77 of FIG. 3 as viewed in the direction indicated by the arrows.

Similar reference characters refer to similar parts throughout the several views of the drawing.

Having reference now to the drawing in detail, and more particularly to FIG. 1, the switch assembly incorporating the instant inventive concept is generally indicated at 10 and includes a housing 11 which consists of an upper circular support 12 which is provided with an annular depending flange 13 having an annular shoulder 14 formed about the lower periphery thereof. Housing 11 also includes a lower portion or support 15 which is comprised of an annular ring 16 having a central circular web 17 dividing the ring into upper and lower flange portions 13 and 19. When the device is assembled, the flange 18 seats against the shoulder 14. Upper and lower support members 12 and 15 are comprised of any desired non-conductive material such, for example, as plastic.

Lower flange 19 seats in an annular groove 20 formed about the periphery of a circular disc 21 which is secured as by means of rivets 22 to web 17. Disc 21 is preferably comprised of insulating material and includes a central boss 24 which is externally threaded as at 25. An annular groove 26 is positioned between the bottom of disc 21 and the top of threaded boss 24. Web 17 is provided with a central opening 27 which is aligned with a larger central opening 28 which extends through disc 21 and boss 24. A pressure exerting punger 29 extends through opening 27, and comprises a part of an enlarged piston 3t? having a head 31 which is linearly movable in opening 22, in a manner to be more fully described hereinafter. The abutment of head 31 with the underside of web 17 serves as a stop limiting the upward movement of plunger 29.

Any desired means may be employed for imparting linear movement to piston 3'8, hence plunger 29, but in the illustrative form of the invention herein shown, take the form of a pressure actuated diaphragm 35 which is mounted at the end of a piston 36 carried by a tubular boss 37 into which the end of piston 39 extends. Piston 35 is linearly movable in a recess 38 in the upper half of a double flanged fitting generally indicated at 40 and including first or lower flange 41 comprising a part of a tubular member 42 having an upper flange 43. Tubular member 42 is internally threaded as at 44 and is engaged by the external threads 25 of boss 24. A set screw 45 extending through a radial bore 46 in flange 43 serves to hold lower support or housing member 15 in closely juxtaposed relation with the top of flange 43.

Positioned interiorly of internally threaded tubular member 42 is an externally threaded block 47 which is held in adjusted position by means of a set screw 48 extending through a suitable threaded opening in the wall of tubular member 42. Block 47 has a central bore 49 opening into an enlarged recess 50 through which piston 30 extends. A coil spring 51 surrounds boss 37 and piston 3t) and engages at its lower end an annulus S2 surrounding boss 37, and normally biases piston 36 in dia phragm 35, and consequently, plunger 29 downwardly.

Lower flange 4 1 is secured as by bolts 54 to the ad jacent flange 53 and an internally threaded pipe member 55, which has a reduced bore 56 therein adjacent diaphragm 35. Pipe is adapted to be connected to any suitable source of pressure, which pressure, when it exceeds the pressure exerted by the spring, serves to move piston 30 and hence plunger 29 upwardly to actuate the switch mechanism of the instant invention in a manner to be described more fully hereinafter.

A first contact bolt 6!? extends through the insulating material of support 12 and carries at its lower end a conductive strip 61 which carries at its opposite extremity a first or upper contact member 62. Contact member 62 is vertically aligned with an opposite or lower contact member 63 which is carried in turn by a spring'arm 64 the opposite end of which is secured by a screw 65 in the lower end of a conductive sleeve 66 which in turn is carried by and in electrical association with a second contact bolt 67. The upper ends of contact bolts 69 and 67 may carry spring wire connecting clips all 68 and 69 respectively for connection to an appropriate circuitry.

A beryllium copper contact arm generally indicated at 7t carries on the opposite faces of one end thereof opposed contacts 71 and '72 which are aligned with and adapted to be respectively engaged by contact members 62 and 63.

Contact arm 7t) is longitudinally split to provide a center section 73 and a pair of opposite side sections 74. The side sections 74 are slightly bowed as best shown in FIG. 6, so as normally to bias contact 71 into electrically contacting engagement with contact member as to close a circuit therethrough, the opposite side of the circuit being closed in a manner to be more fully described hereinafter.

A center section 73 is similarly bowed, but to a greater extent than are the side sections 74, so that pressure imparted to the bowed section 73 which is prestressed between the side sections 74 will occasion reversal of the curvature of bowed sections 74 with a snap spring action which, when etfectuated, will cause the substantially instantaneous movement of contact 72 into engagement with contact member 63 and simultaneously break the circuit between contact 71 and contact member 62.

The opposite end of contact arm 7t) is mounted in cantilever fashion between a first or upper spring stop 75, and a second or lower spring stop 76. Upper spring stop 75 is spaced from the top surface of the contact arm 7d by means of a conductive block 77. It is provided with two split side portions 78 which are bowed downwardly to form abutments which engage side sections 74- of contact arms 7d, the spacer block 77 permitting normal relatively light engagement of the abutment 78 with the upper surface of sections 74. Lower spring stop 76 has an oifset portion St at an intermediate point which spaces the outer end thereof from the underside of contact arm 7t), the spaced outer end carrying a central abutment 81 which is positioned normally for engagement with an intermediate point of the bowed center section 73.

The assembly comprised of contact arms 7%, block 77 and upper and lower spring stops 7S and 76 is secured together at the end opposite contacts 71 and 72 as by means of rivets 82, between which is a bore or opening 83, through which extends a common electrically conductive contact bolt 34. Bolt 34 is surrounded by a spacer sleeve 85 which bears against the top of upper spring stop 75, and the assembly is held in position by means of a nut as below lower spring stop 76, the entire assembly thus being mounted as a cantilever. wire connecting clip 87 may be secured to the upper end of common contact bolt 84 exteriorly of the top of support 12.

The central or free end of spring stop 76 adjacent abutment $1 is positioned immediately over and normally in contact with plunger 29 so that pressure exerted on diaphragm 35 transmitted to plunger 29 moves spring stop 76 and its central abutment 81 upwardly to apply pressure to bowed central section 73 and effectuate the snap action of contact arm Iii previously referred to.

Adjustable stop means are provided for limiting the upward movement of upper spring stop 75 and a consequent movement of side section 74 when pressure is imparted to bowed center section 73 by plunger 29 to take the form of an adjustable screw 99 which extends through an interiorly threaded bushing 91 seated in a central opening in top support or housing 12 and which may be suitably adjusted to engage the central portion of upper spring stop 75 to limit or vary the path of travel required of the plunger 29 to eifectuate the above described snap action. An external lock nut 92 permits the locking of adjacent screw 9% in predetermined position.

Upper and lower supports 12 and 15 may be secured in related assembly in any desired manner, as, for example, by oppositely disposed bolts 93 which extend through suitable openings 94 and top support 12 and engage in threaded bores 95 in web 17.

From the foregoing the operation of the device should now be readily understandable. When the pressure exerted through opening exceeds a predetermined limit, diaphragm 35 will be moved upwardly against the pressure of spring 51 to cause plunger 29 to move spring stop "/6 and its associated abutment 81 upwardly to bow center section 73 oppositely and reverse the curvature of side section 74 with a snap action and to move contact 72 into engagement with contact member 63 closing circuit between wire engaging clip 69 and wire engaging contact clip 87 simultaneously breaking circuit between common contact clip 37 and clip 6%). Upon relief of the pressure on diaphragm 35, the natural curvature of bowed center section 73 will cause the same to return to its normal position again reversing the curvature of side section 74- and reengaging contact 71 with contact member 62, simultaneously breaking circuit between contact '72 and contact member Adjustment of the path of travel of contact may be readily etfectuated by the adjacent screw and the tension of spring 51 may be adjusted by disassembly of the mechanism by releasing set screw 4-5 and unthreading boss 24, and then releasing set screw 48 and rotating threaded block 47 to vary the effective distance between the top of recess 5%} and annulus 52, and hence the compression of spring 51 and the pressure required to be exerted against diaphragm 35 to force plunger 29 upwardly.

From the foregoing it will now be seen that there is herein provided an improved snap action switch which accomplishes all of the Objects of this invention and others, including many advantages of great practical utility and commercial importance.

As many embodiments may be made of this inventive concept, and as many modifications may be made in the embodiment hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted merely as illustrative and not in a limiting sense.

I claim:

A snap action switch comprising, in combination, a pair of oppositely disposed insulated supports comprising portions of a separable housing, a pair of aligned spaced apart contact members carried by said supports, each contact member being carried by the free end of a resilient metal member, and an electrically conductive post carrying the other end of each resilient metal member, said posts being spaced apart and said resilient metal members extending towards each other at an obtuse angle to align said contact members, an elognated resilient contact arm having opposed contacts on opposite sides thereof at one end, said one end extending between said contact members for selective engagement of one or the other of said contacts with an opposed contact member, said contact arm being longitudinally slotted to form a center section and side sections, said side sections being bowed and centrally convoluted normally to bias one of said contacts into engagement with one of said contact members, said center section being bowed out of the plane of said side sections, a first spring stop on one side of said contact arm, said first spring stop comprising a flat metal plate of a width substantially equal to that of said contact arm and including an end portion offset outwardly relative to the contact arm and a centrally positioned inwardly extending abutment engageable with the bowed center section of said contact arm, a second spring stop on the other side of said contact arm, said second spring stop comprising a fiat metal plate of a width substantially equal to that of said contact arm and having a central portion overlying the abutment of said first spring arm, and a pair of short longitudinal slots on opposite sides of said central portion overlying the slots of said contact arm and defining short side arms, each short side arm being convexed inwardly relative to the contact arm to form spaced abutments for the side sections of said contact arm and being aligned with one of the convolutions in said side sections, rivet means securing the aligned ends of said spring stops to the other end of said contact arm, in spaced relation thereto, a common contact bolt mounting said securing means on one of said supports, said contact arm and spring stops being mounted as a cantilever, means comprising an adjustable screw extending through a threaded bore carried by one of said supports limiting movement of the center section of said second spring stop, and means comprising a pressure operable linearly movable rod aligned with said screw for exerting pressure on the other of said spring stops whereby said abutments upon the exertion of said pressure reverse the bow in said center sections to bow said contact arm oppositely to move the other of said contacts into engagement with the other of said contact members with a snap action.

References Cited by the Examiner UNITED STATES PATENTS 2,700,079 1/55 Haydon ZOO-67 2,788,640 4/57 Newberry 20083 BERNARD AGILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

